Passage Three From the beginning, migratio

题型:单项选择题

问题:

Passage Three

From the beginning, migration has been 6ne of the most conspicuous features of human history. Humanity did not appear simultaneously all over the earth but, according to the current scientific consensus, first evolved in Africa, and from there spread far and wide. Even after mankind had populated most of the planet, migration continued to play a decisive role in history down the centuries, as people contended for territory and the resources that go with it. In many of history’s biggest movements of people, the migrants were not volunteers. In the 17th and 18th centuries, 15 million people were taken as slaves from Africa and shipped to Brazil, the Caribbean and North America. In the 19th century, between 10 and 40 million indentured workers (契约工人,苦力) were sent in vast numbers around the world, mainly from China and India.
The 20th century’s wars in Europe and Asia displaced millions more. But perhaps the most intense episode of migration-under-duress (强迫) in modern times occurred after the partition of India in 1947, when 7 million Muslims fled India for the new state of Pakistan and 7 million Hindus fled in the opposite direction.
As individuals, not merely as members of races or religions in flight, people have always traveled in search of a better life. Between the middle of the 19th century and the start of the second world war, 60 million people left Europe and move overseas to the United States, Canada, Latin America, Australia, New Zealand and South Africa. Much of this movement was guided by economic calculation. Most modern migration is of this kind, though nowadays the pull is high wages rather than cheap land.
For the 19th century or so, the pattern of migration has shifted a good deal, with changes in government policy playing a key role. Until t914 governments imposed almost no controls. This allowed the enormous 19th-century movement of migrants from Europe to North America.
Between 1914 and 1945; partly reflecting security concerns, migration was curtailed. Many countries excluded immigrants. America’s Congress passed laws aiming to preserve the country’s racial and religious makeup.
After 1945 came another great change. Many European countries faced labor shortages. Governments actively recruited immigrants for jobs in their expanding industries. Migration surged again, now not mainly from Europe to North America but from the developing countries to the rich ones.
The next big change came in the 1970s. The rich countries were no longer growing quickly and struggling with labor shortages. Recession came to Europe and America, and immigration rules were tightened again. This more restrictive regime continues to apply.

The last paragraph tells us that ______ .

A.Europe and America are still faced with labor shortage

B.Europe and America are not growing economically now

C.recession continues to affect Europe and America

D.immigration rules are still tightened now in Europe and America

考点:在职联考在职联考外国语(英、俄、日)在职攻读硕士联考英语
题型:单项选择题

在现况研究中,通过调查通常可以获得

A.发病率

B.患病率

C.罹患率

D.死亡率

E.病死率

题型:单项选择题

错配修复是基于对复制期间产生的错配的识别。下列叙述正确的是()。

A.UrvABC系统识别并靠DNaseI促使正确核苷酸酸的引入而使错配被修复

B.假如识别发生在被重新甲基化的半甲基化DNA之前,那么修复可能偏向野生型序列(Dam甲基化、MutH、MutSL)

C.错配一般由单链交换所修复,这要靠RecA蛋白恢复正常拷贝序列的能力

D.错配修复也可被认为对DNA的修饰活动,如去烷基化或再氨基化,但是不会替换损伤的核苷酸

E.错配修复是靠正常情况下被LexA蛋白抑制的修复功能完成的(SOS反应)

题型:单项选择题

为什么说高压操作可在一定程度上降低焦比?

题型:单项选择题

正常情况下车站大系统由()系统自动控制。

题型:单项选择题

属于缓冲区

A.牙槽嵴
B.磨牙后垫
C.切牙乳突
D.颊侧前庭
E.黏膜腺导管开口

更多题库